der

// WP_Query arguments
$args = array(
	'post_type'              => array( 'cpt_convention' ),
	'nopaging'               => true,
	'posts_per_page'         => '100',
	'order'                  => 'ASC',
	'tax_query'              => array(
		'relation' => 'AND',
		array(
			'taxonomy'         => 'cpt_speaker',
			'field'            => 'term_id',
			'operator'         => 'IN',
		),
		array(
			'taxonomy'         => 'tax_room',
			'field'            => 'term_id',
			'operator'         => 'IN',
		),
	),
	'meta_query'             => array(
		array(
			'key'     => 'klklö',
			'value'   => 'lkl',
			'compare' => '=',
		),
	),
);

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

// The Loop
if ( $convention->have_posts() ) {
	while ( $convention->have_posts() ) {
		$convention->the_post();
		// do something
	}
} else {
	// no posts found
}

// Restore original Post Data
wp_reset_postdata();