start_date3

$meta_query = array(
	'relation' => 'AND',
	array(
		'key'     => 'start_date3',
		'value'   => '20170426',
		'compare' => '<=',
		'type'    => 'DATE',
	),
	array(
		'key'     => 'end_date3',
		'value'   => '20170426',
		'compare' => '>=',
		'type'    => 'DATE',
	),
);