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tax_query

$tax_query = array(
	'relation' => 'OR',
	array(
		'taxonomy'         => 'pa_rozmiar-felg',
		'terms'            => array( '15', '16', '17', '18' ),
		'field'            => 'slug',
		'operator'         => 'IN',
		'include_children' => true,
	),
);