You shouldn't use windows-1256 as this is Windows OS specific and other OS (i.e. Linux, Apple Mac, etc.) may not render the contents of the page correctly
second, HTML pages can only contain one content type definition. If you wish to combine different content types, you may have to use IFRAMES, but this may complicate things for you.
If you wish to combine Arabic and English words on the same page just use utf-8 which can handle both. For example, if you where to view the content type of http://www.aljazeera.net/Portal
you will find that they use utf-8 and it works for them