Highlight of tags search results.

Command:

GET /megacorp/employee/_search
{ "query" : { "match_phrase" : { "about" : "rock climbing" } }, "highlight": { "fields" : { "about" : {} } } }

Highlighting of search results in CURL:

$curl -XPOST 'localhost:9200/megacorp/employee/_search?pretty' -d '
{
    "query" : 
    {
        "match_phrase" : 
        {
            "about" : "rock climbing"
        }
    },
    "highlight": 
    {
        "fields" : 
        {
            "about" : {}
        }
    }
}'

Highlighting of search results in PHP:

require '../vendor/autoload.php';
$client = Elasticsearch\ClientBuilder::create()->build();
$params = [
            'index' => 'megacorp',
            'type'  => 'employee',
            'body'  => [
                'query' => [
                    'match' => [
                        "about" => "rock climbing"
                    ],                
        ], 
        'highlight' => [
                    "pre_tags"  => "<em>",
                    "post_tags" => "</em>",
                    'fields'    => [
                       'about' => new \stdClass()
                    ]
                ],
            ]
        ];
try {            
    $response = $client->search($params);
} catch (Exception $e) {            
    var_dump($e->getMessage());        
}
var_dump($response);

'about' => new \stdClass() - stdClass it is used for the proper formation of JSON.

Highlighting of search results in Yii2:

$params = [
            'match' => [
                "about" => "rock climbing"
            ]
        ];
$model = Megacorp::find()
                ->query($params)
                ->highlight([
                    "pre_tags"  => "<em>",
                    "post_tags" => "</em>",
                    'fields'    => [
                        'about' => new \stdClass()
                    ]
                ])
                ->all();
var_dump($model);

Additionally

Detailed documentation https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-highlighting.html