And you know in advance that the "jahn" — krivosheinym "john"? Or know, only that pair is a word from the dictionary? If the first — the easiest way stupid character for character.
If the latter — you can try a wildcard search. For example looking for the equivalent of "reccursion":
r*n — too a lot of options?(+1 character)
re*n — still?
accordingly, if you do not succeed, and error in the extreme letters — acting reverse(tecursion):
*ecursion -> *ecursio* -> *cursi* (for example — the correct version is found in the first iteration)
This option usable SQL-LIKE tion and for a grep'