Delete content between string and white space in multiple files

Here is the sample of the content of a file(s):-

string1 strin2 other-string some-other-string foo=bar string(n)

I used _FileListToArrayEx to list all the files with specific extension. Now i am removing specific strings which are not required. I used _ReplaceStringInFile to delete specific string. Hoever i am struck while deleting the string "foo=bar" where "foo=" is common in some of the files and bar can be anything else. So my requirement is to either delete entire foo=bar or delete anything after foo= till white space is reached or insert some-static-string after foo=
Any help is appriciated.