The next major release is still in process, and won't be released for at least two months. However, you can "roll your own" search if you're comfortable building it yourself by building your search terms into the shortcode using the WordPress function "do_shortcode" to build a filter string into the shortrcode....something like:
<?php echo do_shortcode('[pdb_list filter="last_name='.$_GET['last_name'].'&first_name='.$_GET['first_name'].'"]') ?>
It's not easy, but it can be done.
The next update won't actually include a multiple field search, it just makes it a lot easier to do and offer more flexibility in the implementation. It will still be a "roll you own" type situation, but I do plan to offer a plugin that will add this functionality to the main plugin. Again, some months off as it is a major overhaul of the plugin.