1
I requested for more information.
I requested more information.
I asked for more information.
When request is a verb, use request + thing without for: ‘We requested more information.’ ‘She requested a copy of the document.’
With ask, use ask for + thing: ‘We asked for more information.’
When request is a noun, use a request for + thing: ‘We sent a request for more information.’
2
I request you to look into the incident and admit responsibility.
I request that you look into the incident and admit responsibility.
I ask you to look into the incident and admit responsibility.
Do not normally use request + person + to-infinitive.
In formal English, use request that + subject + base form. The base form used in this structure is called the subjunctive: ‘They requested that she leave immediately.’ ‘The manager requested that he be present at the meeting.’
In less formal English, use ask + person + to-infinitive: ‘They asked her to leave.’
See INSIST (1)