WordPress Load More Post via button click

I’m relatively new to WordPress. So this might not be the best approach, or even possible. With that said, I’m open to better solution.

I have a homepage that will display the latest 12 posts.
I want to make a button that when clicked will load the next 4.

What I have currently is this:

<?php query_posts('showposts=4&offset=12'); ?>
    <?php while (have_posts()): the_post(); ?>
        //some html tags
    <?php endwhile; ?>

This will load me the detail of post 13-16.

I’m looking for a way where I can put this in a function and then call it through a jquery click() event where I can use a counter of some sort for the offset. something like

var offSetCounter = 12;

    $(".btnLoadMore").click(function(){
        //php function call
        loadmore(offSetCounter);
        offSetCounter += 4;
    });

So next time i click the button the offSetCounter would be 16 and so on.

Thanks in Advance.