Workfront currently uses the top of the line search system with many options for customization and fast search speeds. This, however, comes at a cost of sacrificing substring searches where substring is a part of the word not starting from the beginning of it. The performance gain from this decision is reducing the time in which results are returned from whole seconds to milliseconds.
For example, in the word "request", "equest" will be considered as a substring and won't provide the results, whereas "reques" will be a partial word from the beginning of the searchable word "request" and will bring you the items containing that word.
The results for "equest" search
The results for "reques" search