Bitcoin 2 of 4 Multisig script with one required
Bitcoin script does not let you require a specific signature, however you could give the person that is required to have a specific signature additional keys and change it to a 4 of 6.
Manager has 3 keys.
Employee 1 has 1 key.
Employee 2 has 1 key.
Employee 3 has 1 key.
With 4 signatures required to spend the Manager only needs one employee present to sign, however the 3 employees can not produce a fully signed transaction without the Manager present as their 3 keys combined does not meet the 4 minimum required.