I found the answer, if it can help !
<?php
date_default_timezone_set('Europe/Paris');
$date_1 = date('Ymd', strtotime("now"));
$date_2 = date('Ymd', strtotime("+12 months"));
?>
<?php
function my_posts_where( $where ) {
$where = str_replace("meta_key = 'evenement_%", "meta_key LIKE 'evenement_%", $where);
return $where;
}
add_filter('posts_where', 'my_posts_where');
?>
<?php
$upcoming_args = array(
'category_name' => '2017',
'post_type' => 'spectacles',
'posts_per_page' => 100,
'meta_key' => 'evenement_%_date_fin_evenement',
'meta_compare' => 'between',
'meta_type' => 'numeric',
'meta_value' => array($date_1, $date_2),
'orderby' => 'meta_value_num',
'order' => 'ASC');
?>
<?php $upcoming_query = new WP_Query( $upcoming_args ); ?>
<?php if ( $upcoming_query->have_posts() ) : ?>
<?php while ( $upcoming_query->have_posts() ) : $upcoming_query->the_post(); ?>
