Giving priority to prefix match in elasticsearch in php

Is there a way in elasticsearch to give more priority for the prefix match than to the string that contains that word?

For ex.- priorities of words if I search for ram should be like this:

Ram Reddy
Joy Ram Das
Kiran Ram Goel
Swati Ram Goel
Ramesh Singh

I have tried mapping as given in here. I have done like this:

$params = ['body' => []];
        foreach ($records as $key => $record) {
            $params['body'][] = [
                'index' => [
                    '_index' => $myIndex,
                    '_type'  => $myType,
                ],
                "mappings"=>[
                    "doc"=>[
                        "properties"=>[
                            "label"=>[
                                "type"=>"text",
                                "fielddata"=> true,
                                "analyzer"=>"whitespace",
                                "fields"=>[
                                    "keyword"=>[
                                        "type"=>"keyword"
                                    ]
                                ]
                            ]
                        ]
                    ]
                ]
            ];
            $record['sr']=intval($record['sr']);
            $params['body'][] = $record;
            if ($key%1000 == 0) { // Every 1000 documents stop and send the bulk request
                $response = $client->bulk($params);
                $params = ['body' => []];  // erase the old bulk request
                unset($response);      // unset the bulk response when you are done to save memory
            }
        }
        // Send the last batch if it exists
        if (!empty($params['body'])) {
            $responses = $client->bulk($params);
        }

and searching like this:

$body = [
    "size" => 100,
    'sort' => [
        ["type"=>["order"=>"asc"]],
        ["sr"=>["order"=>"asc"]],
        ["propLabels"=>["order"=>"asc"]],
        ["value"=>["order"=>"asc"]]
    ],
    '_source' => $select,
    'query' => [
        'bool' => [
            'must' => $must_query,
            'must_not'=>$removeFilter
         ]
     ]
];

$params = [
    'index' => $myIndex,
    'type' => $myType,
    'body' => []
];
$params['body'] = $body;
$response = $client->search($params);

But while searching I'm getting the error:

{"error":{"root_cause":[{"type":"illegal_argument_exception","reason":"Fielddata is disabled on text fields by default. Set fielddata=true on [type] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory."}],"type":"search_phase_execution_exception","reason":"all shards failed","phase":"query","grouped":true,"failed_shards":[{"shard":0,"index":"filter_200_12662","node":"ePcgM3YVRzKz59RH5Hcz1g","reason":{"type":"illegal_argument_exception","reason":"Fielddata is disabled on text fields by default. Set fielddata=true on [type] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory."}}],"caused_by":{"type":"illegal_argument_exception","reason":"Fielddata is disabled on text fields by default. Set fielddata=true on [type] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory."}},"status":400}

Is there any other way to sort the results for the search in the relational database using the search method in php?

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