Query images for Slider for conciertos

// WP_Query arguments
$args = array(
	'p'                      => '$post_id',
	'post_type'              => array( 'conciertos' ),
	'post_status'            => array( 'publish' ),
	'meta_query'             => array(
		array(
			'key'     => 'imagen-adicional-slider-2',
			'compare' => 'EXISTS',
			'type'    => 'CHAR',
		),
	),
);

// The Query
$query = new WP_Query( $args );