functions.php

<?php

/**
 * Create new 'meta_content` filter.
 *
 * Recreate the default filters applied to `the_content`, 
 * so content retrieved using `get_post_meta` can be 
 * formatted in the same way.
 */
add_filter( 'meta_content', 'wptexturize' );
add_filter( 'meta_content', 'convert_smilies' );
add_filter( 'meta_content', 'convert_chars' );
add_filter( 'meta_content', 'wpautop' );
add_filter( 'meta_content', 'shortcode_unautop' );
add_filter( 'meta_content', 'prepend_attachment' );