is not a whitespace character, as far as regexpes are concerned. You need to either modify the regexp to include those strings in addition to \s, like /(\s| |%20)/, or previously parse the string contents to get the ASCII or Unicode representation of the data.
You are mixing abstraction levels here.
If, what after a careful reread of the question seems to be the case, you are after a way to match all whitespace characters referring to standard ASCII plus the whitespace codepoints, \p{Z} or \p{Zs} will do the work.
You should really clarify your question because it has misled a lot of people (even making the correct answer to have some downvotes).