WPDB Update using Conditional Arrays

This is not posible with $wpdb->update(). If you check the source code, you will see these lines (lines 2150 – 2161), there is no way getting an OR in there:

foreach ( $where as $field => $value ) {
    if ( is_null( $value['value'] ) ) {
        $conditions[] = "`$field` IS NULL";
        continue;
    }

    $conditions[] = "`$field` = " . $value['format'];
    $values[] = $value['value'];
}

$fields = implode( ', ', $fields );
$conditions = implode( ' AND ', $conditions );

---

However, you can write your own query using prepare()

$wpdb->query($wpdb->prepare(
    "UPDATE `$tbl_request_log` SET `status` = false WHERE (`id` = %d OR `id` = %d) AND `status` = true",
    $req1_id,
    $req2_id
));