A user can display custom fields value on overlays. Here a very easy steps are given a user can display custom fields on overlay.
customfieldoverlay

Follow some steps to display custom fields on overlays :-
customfieldimage

Step 1 First add custom field in post
Step 2 Go to post page and give the name and value of custom field
Step 3 Now Click on Settings menu of WP Overlay plugin

Step 4 Now in Overlay Content give the custom field name {{%custom_field_name%}} this is placeholder copy this placeholder and past in text area and type the custom field name between two percentage sign {%…..%}

Step 5 At the end click on Save Settings button

Custom Field value displaying on overlay

customfieldoverlayfrontend

Video Tutorial