In regex form:
Ols(o|e)n
or
Ols.n (for any one character not just o and e).
As a BASH pattern match
Ols[oe]n or Ols?n
In a windows search dialog:
Ols?n
And if you really wanna be sloppy
Ols*n will of course work in all of those but the regex which would need to look like Ols.*n but you wouldn't want to do that anyway because that matches any number of chars.
Any real regex engine will recognize "ols[oe]n" as a shorthand for "ols(o|e)n". Some attention to detail, Andy.