[ADMIN] Partial substrings in FTS

[A J]

In FTS, how do I search for partial substrings that don't form a English word.
Example, in the text: 'one hundred thirty four'  I want to find the records 
based on 'hun'

SELECT to_tsvector('one hundred thirty four') @@ to_tsquery('hun');
does not return anything.

Thanks.