Category list from custom taxonomies.

<?php
    $tags = wp_get_post_terms($post->ID, 'client_name');
    $args = array (
                'tax_query' => array (
                    'taxonomy' => 'client_name',
                    'terms' => $tags[0]->term_id
                    ),
                'post_type' => 'project'
                );

    $query = new WP_query($args);
        if ( $query->have_posts() ) : {
            while ( $query->have_posts()) : $query->the_post();
            $postcats = get_the_term_list($post->ID,'project_type','','','');
                if ($postcats) {
                        foreach($postcats as $cat) {
                            $all_cats_arr[] = $cat -> name; //USING JUST $cat MAKING $all_cats_arr A MULTI-DIMENSIONAL ARRAY, WHICH DOES WORK WITH array_unique
                        }
                    }
                endwhile;
                }
            endif;
    $cats_arr = array_unique($all_cats_arr); //REMOVES DUPLICATES
    echo '<li>'.print_r($cats_arr, true).'</li>'; //OUTPUT FINAL CATS
    wp_reset_query();
?>