relevanssi_hits_filter

/** Relevanssi customization by max **/
add_filter('relevanssi_hits_filter', 'order_the_results');

function order_the_results($hits) {
    global $wp_query;
    if ($wp_query->query_vars['orderby'] == 'likes') {
        $likes = array();
        foreach ($hits[0] as $hit) {
            $likecount = get_post_meta($hit->ID, '_likes', true);
            if (!isset($likes[$likecount])) $likes[$likecount] = array();
            array_push($likes[$likecount], $hit);
        }
        ksort($likes);
        $sorted_hits = array();
        foreach ($likes as $likecount => $year_hits) {
            $sorted_hits = array_merge($sorted_hits, $year_hits);
        }
        $hits[0] = $sorted_hits;
    }
    return $hits;
}