It is better to modify WordPress search SQL query instead of adding extra meta query.
try this:
function search_distinct($distinct) {
$distinct="DISTINCT";
return $distinct;
}
function join_table($join){
global $wpdb;
$join .= "LEFT JOIN $wpdb->postmeta ON ($wpdb->posts.ID = $wpdb->postmeta.post_id) ";
return $join;
}
function search_into_post_meta( $search, $wp_query )
{
if ( is_search() ) {
global $wpdb;
if ( empty( $search ) )
return $search;
$q = $wp_query->query_vars;
$n = ! empty( $q['exact'] ) ? '' : '%';
$search =
$searchand = '';
foreach ( (array) $q['search_terms'] as $term ) {
$term = esc_sql( like_escape( $term ) );
$search .= "{$searchand} ( ($wpdb->posts.post_title LIKE '{$n}{$term}{$n}') OR ($wpdb->posts.post_content LIKE '{$n}{$term}{$n}') OR ($wpdb->postmeta.meta_key = 'post_state' AND $wpdb->postmeta.meta_value LIKE '{$n}{$term}{$n}') OR ($wpdb->postmeta.meta_key = 'post_region' AND $wpdb->postmeta.meta_value LIKE '{$n}{$term}{$n}') OR ($wpdb->postmeta.meta_key = 'post_country' AND $wpdb->postmeta.meta_value LIKE '{$n}{$term}{$n}'))";
$searchand = ' AND ';
}
if ( ! empty( $search ) ) {
$search = " AND ({$search}) ";
if ( ! is_user_logged_in() )
$search .= " AND ($wpdb->posts.post_password = '') ";
}
add_filter('posts_distinct_request', 'search_distinct');
add_filter('posts_join_request','join_table');
return $search;
}
return $search;
}
add_filter( 'posts_search', 'search_into_post_meta', 500, 2 );