functions

<?php
function charity_qvs($qv) {
    $qv[] = 'cat_charities';
    $qv[] = 'demographic_charities';
    $qv[] = 'intention_charities';
    $qv[] = 'community_focus_charities';
    return $qv;
}

/**
 * Add filter to add Relevansi filtering query vars.
 *
 * @since 1.0.0
 */
add_filter('query_vars', 'charity_qvs');


/**
 * Add Relevanssi taxonomy query.
 *
 * @since 1.0.0
 */
function charity_tax_query($query) {
    $tax_query = array();

    if (!empty($query->query_vars['cat_charities'])) {
        $tax_query[] = array(
            'taxonomy' => 'zdca-cat-charities',
            'field' => 'id',
            'terms' => $query->query_vars['cat_charities']
        );
    }
    /*if (!empty($query->query_vars['demographic_charities'])) {
        $tax_query[] = array(
            'taxonomy' => 'zdca-demographic-charities',
            'field' => 'id',
            'terms' => $query->query_vars['demographic_charities']
        );
    }
    if (!empty($query->query_vars['intention_charities'])) {
        $tax_query[] = array(
            'taxonomy' => 'zdca-intention-charities',
            'field' => 'id',
            'terms' => $query->query_vars['intention_charities']
        );
    }
    if (!empty($query->query_vars['community_focus_charities'])) {
        $tax_query[] = array(
            'taxonomy' => 'zdca-community-focus-charities',
            'field' => 'id',
            'terms' => $query->query_vars['community_focus_charities']
        );
    }*/


    if (!empty($tax_query)) {
        $tax_query['relation'] = 'OR'; // you can also use 'OR' here
        $query->set('tax_query', $tax_query);
    }

    return $query;
}

/**
 * Add filter to add Relevansi filter taxonomy query
 *
 * @since 1.0.0
 */
add_filter('relevanssi_modify_wp_query','charity_tax_query');


/*
 * Fix if Yoast SEO is installed.
 *
 * @since 1.0.0
 * */
add_filter('relevanssi_modify_wp_query', 'rlv_meta_fix', 99);
function rlv_meta_fix($q) {
    $q->set('meta_query', '');
    return $q;
}