Find number of count of a word in column in each row

Question

I have a table name 'answer' and where answer saved given by a user for a question. User give multiple answer of a question.So answer save as string in 'answer' column. My table look like this

id  userid   questionid  answer
 
1   2        5           red,blue,white,green

2   3        5           red,blue

3   5        5           red,white

4   6        5           blue,white,green

5   7        5           red,blue,white,green      

I want to select those userid whose answer 3 value(blue,white,green) or more than 3(red,blue,white,green). I have tried with length function but it not work.