betweendate

$meta_query = array(
	'relation' => 'OR',
	array(
		'relation' => 'AND',
		array(
			'key'     => 'start_date1',
			'value'   => '20170426',
			'compare' => '<=',
			'type'    => 'DATE',
		),
		array(
			'key'     => 'end_date1',
			'value'   => '20170426',
			'compare' => '>=',
			'type'    => 'DATE',
		),
	),
	array(
		'relation' => 'AND',
		array(
			'key'     => 'start_date2',
			'value'   => '20170426',
			'compare' => '<=',
			'type'    => 'DATE',
		),
		array(
			'key'     => 'end_date2',
			'value'   => '20170426',
			'compare' => '>=',
			'type'    => 'DATE',
		),
	),
	array(
		'relation' => 'AND',
		array(
			'key'     => 'start_date3',
			'value'   => '20170426',
			'compare' => '<=',
			'type'    => 'DATE',
		),
		array(
			'key'     => 'end_date3',
			'value'   => '20170426',
			'compare' => '>=',
			'type'    => 'DATE',
		),
	),
	array(
		'key'     => 'start_date1',
		'value'   => '20170426',
		'compare' => '=',
		'type'    => 'DATE',
	),
	array(
		'key'     => 'start_date2',
		'value'   => '20170426',
		'compare' => '=',
		'type'    => 'DATE',
	),
);