Hi Vivek,
I'm not 100% sure if I understand what you want to achieve, but in any case, this search function either searches a keyword across whole facts and attributes or whole datasets name.
If you would like to be able to select only facts within a specific dataset or only attributes, that's currently not possible. Let me know if this what you are up to and I can submit a product feedback. Could you please also elaborate a bit more how would this help you to manage your data so we can better understand your use-case?