You can use tax_query
for Taxonomy Parameters for your WP_Query.
$term_id = $_REQUEST ['soins-taxonomy']; // or use $_POST or $_GET as the case may be
$args = array(
'order' => 'ASC',
'post_type' => 'etablissements',
'tax_query' => array(
array(
'taxonomy' => 'location',
'field' => 'term_id',
'terms' => $term_id,
),
'posts_per_page' => 9,
'paged' => $ourCurrentPage
);
I hope this may help.