wikipedia-elasticsearch-morelikethis.php

<?php

$data = json_encode(array(
	'query' => array(
		'more_like_this' => array(
			'fields' => array('title', 'text'),
			'like_text' => $text,
			'min_term_freq' => 3,
			'max_query_terms' => 50,
			'percent_terms_to_match' => 0.1,
		)
	),
	'size' => 100,
	'fields' => array('id', 'title', 'category'),
));