Can’t stop getting an array when using the $single function

I am using WordPress as my CMS and i’m trying to create a page where users can find a list of articles in a category. I’m basically using a modified version of the WP Classic theme and using the arc-cont.php file as the basis for my page template. I’m putting the category number that i want into a custom field and trying to use that as the variable. I keep getting an “Array” message when i put the code in, and i can’t figure out how to get it to just list the posts that i want.

Below is the code for the entire template.

<?php
/*
Template Name: Archives with Content
*/
?>

<?php
get_header();
?>

<?php if (have_posts()) : while (have_posts()) : the_post(); ?>

<div class="post" id="post-<?php the_ID(); ?>">
	 <h3 class="storytitle"><a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a></h3>
	<div class="meta"><?php the_tags(__('Tags: '), ', ', ' — '); ?> <?php edit_post_link(__('Edit This')); ?></div>

	<div class="storycontent">
		<?php the_content(__('(more...)')); ?>
	</div>

</div>

<?php endwhile; else: ?>
<p><?php _e('Sorry, no posts matched your criteria.'); ?></p>
<?php endif; ?>

<?php posts_nav_link(' — ', __('&laquo; Older Posts'), __('Newer Posts &raquo;')); ?>

</div> <// End page content, begin listing archives>
<div id="content" class="widecolumn">
<?php

      $mykey_values = get_post_custom_values( $key = 'category', $value, $single = true );
      foreach ( $mykey_values as $value ) {
      echo "$key => $value (category=$mykey_values)<br />";
          }

?>
<div id="main">
<h2>Posts relating to this subject:</h2>
    <ul>
        <?php $posts = get_posts('category=$mykey_values');

        if( $posts ) : 

        foreach( $posts as $post ) : setup_postdata( $post ); ?>

        <li><a href="<?php the_permalink(); ?>" title="Link to <?php the_title(); ?>"><?php the_title(); ?></a></li>

        <?php endforeach; ?>

		<?php endif; ?>
    </ul>
</div>
<?php get_footer(); ?>