If by “featured posts” you mean sticky post, those posts should come first. You have to jump through hoops to prevent that. There is likely a filter in your theme or a plugin that is altering that default behavior. Search the /wp-content/ directory for pre_get_posts.
If “sticky posts” is not what you mean, you are missing necessary query arguments but I can’t tell which ones as you don’t explain what constitutes a “featured post”.
Secondly, your query arguments are wrong. 'order' => '$var', instructs the query to order by the string literal $var, which will not work. Variables do not expand inside single quotes. Use double quotes, or, my preference, no quotes at all. You don’t need them.