dates

$date_query = array(
	'relation' => 'OR',
	array(
		'key'     => 'start_date',
		'value'   => 'VAL',
		'compare' => '>=',
	),
	array(
		'key'     => 'end_date',
		'value'   => 'VAL',
		'compare' => '<=',
	),
);