Foreign letters in Google Fonts - by royaltheme-user

Hi,
I am using google fonts in all areas set in the theme options section.
Some of the foreign based fonts inside the content are not shown properly.
After some research şt seems what I need to add is

“subset=latin,latin-ext”

to the related code where google fonts is set, which seems to be

<link rel='stylesheet' id='tp-open-sans-css' href='http://fonts.googleapis.com/css?family=Open+Sans%3A300%2C400%2C600%2C700%2C800&ver=4.2.1' type='text/css' media='all' />

There is a line in shortcodes.php as;
<link rel='stylesheet' href='http://fonts.googleapis.com/css?family=<?php echo $google_name; ?>' type='text/css' media='all' />

added subset=latin,latin-ext inside this shortcode.php line but nothing changed.

Is there any way adding this latin charset addition to google fonts inside the theme?

Thanks in advance