Change part of URL string with variable using with HTACCESS

I need to create a redirect rule that changes only a part of my url string, and some of the string changes according to the page url. this is what I need (need to change the bolded part):

change: https://www.example.com/**category**/**custom-directory-name**/rest-of-the-url/

to: https://www.example.com/**product**/rest-of-the-url/

Thanks in advance.