How to make use an "OR" in link fields

Hi i need to filter a between 2 date range with the link to TASK doctype. These are the formula to used in the filter

Start_b (Start_a Between end_a)
End_B (start_a Between end_a)

I tried using these script but still not working

[‘Task’, ‘exp_start_date’, ‘between’,[start,end]] || [‘Task’, ‘exp_end_date’, ‘between’,[start,end]]

It always display the first parameter but not both. Is there anything that i do wrong? i even tried using the or_filters but still no avail.
Please help thank you