In WordPress Shortcode is a different term please see here Shortcode « WordPress Codex
I think you are referring SHORTCODE as snippet of code here.
Please copy the code of function sparkling_featured_slider from the shared topic and paste it in to your child theme functions.php file replacing your existing snippet of code that you shared above.
After doing this just create a custom field in the slider post in the admin area having name slider_link and add the URL as value in it where you want to redirect the slider post link.