Hi @kstorm
Well, I would suggest you to follow the below link to remove the parts
[guide|99167]
Follow to step 23.
The fan should be holding by with some screws.
remove it and use it as a reference to compare and order replacement.
You can purchase replacement fan at ebay, aliexpress, etc
Example:
https://www.ebay.com/sch/i.html?_from=R40&_nkw=alienware+r4+cooling+fan&_sacat=0&_sop=15