It is currently not possible to check your custom fields when in your Pipelines without opening the whole contact in a new page.
It would be great to be able to choose which fields you wish to view in the Pipelines page / CRM the same way it is possible in the contacts page.
Should we one day be able to do this, it would save a lot of time and effort by allowing you to quickly see the information you need just by clicking on the contacts name and checking the card that pops up.