Unable to do a "Like" on a Clob Field

First the structure of the Table:

Second the SQL statement:
Select CMNT_TXT From TCONTACT Where Upper(CMNT_TXT) Like '%OPIOID%' With Ur;

Third the Error Message:
Lookup Error - DB2 Database Error: ERROR [22001] [IBM][DB2/NT64] Value "%3CP%3E&nbsp" is too long.

Fourth: I am going to have to add or statements to the Where Clause to search for all these values:
Opioid
Opiate
Suboxone
Methadone
Fentanyl
Dilaudid
Oxycodone
Morphine
Hydrocodone
Lorcet
Lortab
Codeine
Withdrawal
Norco
Percocet

Fifth: It was not my idea to make this a "CLOB" field.

Sixth: It was not my idea to allow workers to add special formatting to our program. That decision was made 15 years ago.