The idiom 'to cast out a wide net', means to try or consider a very wide variety of other people or things in order to find what you are looking for. 

1. Kevin was against the idea of promoting someone from within the company to fill the new position. He felt that they should be casting a wide net in order to find the best possible candidate.
2. The entrepreneur felt that she needed to cast out a wider net in her efforts to attract an investor. For that reason, she began making videos online in order to showcase her business. 

1. I asked friends and family if they knew anyone who was interested in renting my spare room but I think I'll cast a wide net and put an ad online too.
2. If you're searching for a romantic partner you want to cast a wide net and meet lots of different people.