Cast about for
Definition 1 of 2
Pro Tip 1/3Uncertain Goal
Use when the aim is unclear or when exploring random possibilities. 
She cast about for interesting topics for her thesis.
Pro Tip 2/3Out of Options
Suggests a situation of last resort or desperation for solutions. 
The stranded hikers cast about for any sign of help.
Pro Tip 3/3Wide Scope
Indicates a broad, unspecific search rather than a focused one. 
The author cast about for anecdotes to include in his book.