All the searches allow the use of the wild-card " * ". This takes the place of any series of letters in the search-term you enter. So, for example, entering "McEntaggert" returns 6 results, while "M*c*n*t*g*rt" (which finds Mackentaggart, MacEntaggert, McIntegert, McEntaggirt etc.) returns 398.
Keep in mind that vowels are where accents live and so are more likely to change in the records.