SUMIF problem looking for specific words within text

Hi,

I'm trying to add everything in Column B if the text in Column A contains a certain piece of text. I've done this by using the following formula:

SUMIF(R:R,"*hello*",S:S)

In the above forumla I'm adding all of column B where column A contains the text "hello". My problem is that I don't know how to tell the forumla to look up text in a cell as opposed to looking for the text "hello". I've attached a sheet that explains the problem better. Alternatively, if someone knows a better way of doing this, I'd love to hear it. I enjoy looking at different ways of doing the same thing in Excel .

Thanks