directory_listing_hidden

$meta_query = array(
	'relation' => 'OR',
	array(
		'key'     => 'is_hidden',
		'value'   => '1',
		'compare' => 'NOT LIKE',
		'type'    => 'CHAR',
	),
	array(
		'key'     => 'is_hidden',
		'value'   => '1',
		'compare' => 'NOT EXISTS',
		'type'    => 'CHAR',
	),
);