How to get post_content while the post is being edited

I'm building a plugin that uses custom posts. The custom post uses metaboxes but some of the meta fields need information typed in the post editor.

I'm trying to use post_content to retrieve whatever is in the post editor, but it's either empty, or it only returns what has been previously saved.

Is there anyway to retrieve the post content at anytime during the edit, without having to save the post first?

Thanks you in advance!