Case insensitive search in utf8 db

[John Stergiou]

I have a db with uft8 values in greek like:
ΓΙΑΝΝΗΣ
Γιάννης
Γιαννης
(it is the word John in greek) and I want to write a query to be able to find all these 3 instances. In other words, I have words in upper case, words in lower case, words with or without tonos (= the mark ' on letter α, second row in my example). Also, another word may be before or after that word. I tried adding " COLLATE NOCASE" at the end of the query and didn't help. Tried: SELECT * FROM Table WHERE UPPER(item) LIKE 'UPPER(%text%')
and now I can find ΓΙΑΝΝΗΣ when searching for "γιαννησ". The last letter "ς" is handled as different than "Σ" as the lower case of "Σ" is "σ" (when a greek word ends with "σ", we use "ς" instead). What can I do to deal with it?