Random posts on homepage

Hi everybody,

I’m using the following code to display the 4 recent posts on the main page:

<!-- Recent Blog Posts -->
    <?php
    //get post type ==> regular posts
        global $post;
        $args = array(
            'post_type' =>'post',
            'numberposts' => '4'
        );
        $blog_posts = get_posts($args);
    ?>
    <?php if($blog_posts) { ?>
        <section id="home-posts" class="clearfix">
            <h2 class="heading"><span><?php if(!empty($options['recent_work_text'])) { echo $options['recent_news_text']; } else { _e('Die neuesten Rezensionen','adapt'); }?></span></h2>
            <?php
            $count=0;
            foreach($blog_posts as $post) : setup_postdata($post);
            $count++;
            //get portfolio thumbnail
            $feat_img = wp_get_attachment_image_src(get_post_thumbnail_id(), 'grid-thumb');
            ?>

            <article class="home-entry <?php if($count == '4') { echo 'remove-margin'; } if($count == '3') { echo ' responsive-clear'; } ?>">
            	<?php if ($feat_img) {  ?>
                <a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>" class="nodec"><div class="caption"><img src="<?php echo $feat_img[0]; ?>" height="$feat_img[2]" width="$feat_img[1]" alt="<?php echo the_title(); ?>"><figcaption><?php the_date(); ?></figcaption></div></a>
                <?php } ?>
                <div class="home-entry-description">
<h2 class="main"><a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>"><?php echo the_title(); ?></a>		</h2>
			<i style="letter-spacing: 1px;">von <?php the_category(' '); ?></i>
                </div>
                <!-- /home-entry-description -->
            </article>
            <!-- /home-entry-->
            <?php
            if($count == '4') { echo '<div class="clear"></div>'; $count=0; }
            endforeach; ?>
        </section>
        <!-- /home-posts -->
    <?php } ?>

Is there any way to alter that code in order to show 4 random posts excluding the recent 4 ones from that random selection?

Thanks in advance.